This invention relates to a device or tool for establishing a marked line at a known angular relationship to an already established line and has particular utility in the field of carpentry although not necessarily limited thereto. When it is desired to build a wall at a certain angular relationship (normally 90.degree.) from an already existing wall, the carpenter or other craftsman will either by the use of a protractor, square or other angle measuring device, mark two or more reference points on the subfloor and thereafter by use of a taut chalked line snap a reference line along those points so as to establish a marked line at the desired angle with the existing wall. This leads to inherent inaccuracies inasmuch as the square, protractor or other angle measuring device is normally relatively small for ease in portability and therefore can only establish spaced points a relatively short distance from the wall such that when the reference line is formed by passing through those points, substantial inaccuracies can occur especially if the wall or other structure is to be built of a considerable length.
One possible way to at least partially overcome this problem would be to utilize a line marker of the construction shown in U.S. Pat. No. 2,524,596 issued Oct. 3, 1950. Such a device is, however, primarily limited to bisecting an angle and accordingly forming a 90.degree. reference line from a base line and is of undesirably cumbersome construction. An addition desirable feature of the present invention would be to provide a device which similarly is not limited in the formation of 90.degree. reference lines but is able to equally form reference lines at other angles, e.g., 45.degree., 60.degree., etc.
Other patents of which the present applicant is aware but which are also believed to have only incidental bearing on the present invention are U.S. Pat. No. 2,507,460 issued May 9, 1950 and U.S. Pat. No. 756,632 issued Apr. 5, 1904.
It would accordingly be desirable to provide a device or tool of the above-described type which can conveniently and easily form a reference line with respect to an already established base line at various predetermined angles and which line has a great degree of accuracy over the entire length of the established reference line. These and other objects of the present invention are accomplished by a tool including an elongated member having generally parallel front and rear walls, said rear wall adapted for disposition along said established base line, a pair of angle lines each mounted on support means in turn attached to said member, said angle lines adapted for respective extension and retraction with respect to the front wall of said member at a pair of spaced locations therealong, a marking line associated with said member and adapted for extension from said front wall thereof at a first guide point centrally intermediate the locations where said angle lines are adapted to extend from said member front wall, and means associated with said angle lines to predetermine the respective lengths that said lines extend from said front wall thereof such that the intersection of said angle lines in front of said member defines a second guide point such that said marking line will define said predetermined angle with said member front wall when aligned along first and second guide points.
Other objects, features and advantages of the invention shall become apparent as the description thereof proceeds when considered in connection with the accompanying illustrative drawing.